In plunger-type folding machines carton blanks are moved along a slideway to be engaged by glue wheels which apply glue to selected flaps of the carton prior to folding. There are circumstances however, when it is desired to have the glue placed in spots of predetermined size and location in order to minimize glue consumption and to avoid the risk of having excessive glue squeezed out from between panels of folded cartons. In some machines this has been accomplished, to some extent by interrupting the peripheral surface of the glue wheels so that they do not apply a continuous strip. However, there still occurs some relative sliding as the carton accelerates and then decelerates over the slideway. Hence, precise glue application is not readily achieved.